Double cavity toroidal-type continuously variable transmission

Abstract

A double cavity toroidal-type containing variable transmission, in which one of two input disks is fixed to an input shaft, the other input disk and an output disk are supported so as to be movable in the axial direction thereof, and the other input disk is energized toward one input disk by a cylinder, and power rollers 66 respectively stored in a pair of cavities are contacted with the input and output disks. The input shaft is allowed to shift in the axial direction thereof, whereas the output shaft is prevented from shifting in the axial direction thereof. A drive gear formed in the output disk and a driven gear formed in the output shaft are respectively composed of double helical gears.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a double cavity toroidal-type continuously variable transmission including a pair of cavities defined by input and output disks with which a power roller can be contacted.

2. Description of the Related Art

Such double cavity toroidal-type continuously variable transmission is known from JP-A-8-159229 and JP-A-2000-46145.

In the double cavity toroidal-type continuously variable transmission disclosed in JP-A-8-159229, an input shaft supporting a pair of continuously variable transmission mechanisms is axially positioned in a casing by a torque-cam-mechanism-side bearing disposed on one of the shaft end portions of the input shaft, and a double helical gear formed in a pair of output disks are threadedly engaged with a double helical gear formed in an output shaft.

Also, in the double cavity toroidal-type continuously variable transmission disclosed in JP-A-2000-46145, an input shaft supporting a pair of continuously variable transmission mechanisms is structured such that the two shaft end portions thereof are axially positioned in a casing.

By the way, a double cavity toroidal-type continuously variable transmission of this kind includes a pair of input disks respectively disposed on the two end portions of an input shaft and a pair of output disks respectively disposed on or formed integral with the central portion of the input shaft. One of the input disks is fixed to the input shaft and the output disks or the other input disk is supported on the input shaft so as to be slidable in the axial direction of the input shaft. By energizing the other input disk toward one input disk using a torque cam mechanism or an oil pressure cylinder, power rollers are respectively pressed and held by and between one input disk and the output disk as well as by and between the other input disk and the output disk to thereby transmit torque between them.

However, in the case where the power rollers are pressed and held by and between the input and output disks as a result of the load of the torque cam mechanism or oil pressure cylinder, the contact portions of these parts and the disks themselves are elastically deformed to a slight degree to thereby change or narrow the distance between the input and output disks and it is known that the sum of the respective deformation quantities reaches the unit of mm. As in the double cavity toroidal-type continuously variable transmission disclosed in JP-A-8-159229, in the case where one end portion of the input shaft is supported on the casing in such a manner that it is immovable in the axial direction, with the above-mentioned change of the distance between input and output disks, the axial-direction position of the central output disk varies to thereby shift the meshing engagement between the double helical gear formed in the output disk and the double helical gear formed in the output shaft.

To solve such a problem, it is necessary that the double helical gear formed in the output disk is divided into two helical gears having opposite tooth groove directions and a thrust bearing is interposed between the two helical gears to thereby allow the two helical gears to rotate with respect to each other. However, this complicates the structure. Also, a large torque is required to allow the two helical gears to rotate with respect to each other and also this torque appears as a transmission torque difference between the two helical gears. Therefore, thrust forces, which are applied to the two helical gears from the double helical gear of the output shaft, are caused to differ from each other. The different thrust forces cause an imbalance between the loads received by the right and left power rollers. This raises a fear that the characteristics of the right and left continuously variable transmission mechanisms can differ from each other.

Also, on receiving the load from the torque cam mechanism or oil pressure cylinder, the input shaft is extended in the axial direction. In this case, as in the double cavity toroidal-type continuously variable transmission disclosed in JP-A-2000-46145, in the case where the two end portions of the input shaft are supported on the casing so as to be immovable in the axial direction, there arises a problem that large loads can be applied to the casing from the bearings disposed on the two end portions of the input shaft.

To solve the above problem, the input shaft may be supported on the casing so as to be movable in the axial direction. In this case, however, unless there is arranged some positioning means, there is a possibility that the input shaft can move arbitrarily.

SUMMARY OF THE INVENTION

The present invention eliminates the drawbacks found in the above-mentioned conventional double cavity toroidal-type continuously variable transmission. Accordingly, it is an object of the invention to provide a double cavity toroidal-type continuously variable transmission in which, while positioning an input shaft in the axial direction thereof, not only the load of the input shaft is prevented from being transmitted therefrom to a casing, but also loads to be applied to two power rollers respectively stored in a pair of cavities can be prevented from differing from each other.

In attaining the above object, according to a first aspect of the invention, there is provided a double cavity toroidal-type continuously variable transmission including one of a pair of input disks which is fixed to the axial-direction outer portion of an input shaft, where the other input disk is supported so as to be movable in the axial direction thereof, and an output disk is supported on the axial-direction inner portion of the input shaft so as to be movable in the axial direction thereof; the other input disk is energized toward the one input disk by an energizing unit; power rollers respectively stored in a pair of cavities formed between the mutually opposing input and output disks are contacted with the input and output disks; and, a drive gear formed in the output disk is meshingly engaged with a driven gear formed in output shaft, wherein each of the power rollers is rotated around a trunnion shaft to vary its contact positions with the input and output disks, thereby being able to achieve gear change, and further wherein the input shaft is allowed to shift in the axial direction thereof, the output shaft is prevented from shifting in the axial direction thereof and the mutually meshingly-engageable drive and driven gears are respectively composed of double helical gears which are prevented from rotating with respect to each other.

According to the above structure, even in the case where the axial-direction position of the output disk with respect to one input disk fixed to the input shaft is varied by the energizing force of the energizing unit energizing the other input disk, which is supported on the input shaft so as to be movable in the axial direction thereof, toward one input disk, because the axial-shift allowed input shaft and the axial-shift restricted output shaft are connected together by drive and driven gears respectively composed of double helical gears which are prevented from rotating with respect to each other, the axial-direction shift of the input shaft can be restricted by the output shaft. As a result of this, while positioning the input shaft in the axial direction, not only the load of the input shaft can be prevented from being transmitted therefrom to the casing but also the loads, which are applied from the energizing unit to the power rollers stored in the pair of cavities, can be prevented from differing from each other.

By the way, the first shaft 14 employed in the illustrated embodiment corresponds to the output shaft according to the invention, the double helical gear 23 employed in the illustrated embodiment corresponds to the driven gear according to the invention, the output gear 25 employed in the illustrated embodiment corresponds to the drive gear according to the invention, and the cylinder 71 employed in the illustrated embodiment corresponds to the energizing unit according to the invention, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a skeleton view of a continuously variable transmission according to a first embodiment of the invention;

FIG. 2 is a map of the layouts of the above continuously variable transmission shown in FIGS. 3-5;

FIG. 3 is an enlarged view of the A part shown in FIG. 2;

FIG. 4 is an enlarged view of the B part shown in FIG. 2;

FIG. 5 is an enlarged view of the C part shown in FIG. 2;

FIG. 6 is a section view taken along the line VI--VI shown in FIG. 3;

FIG. 7 is an enlarged view of the main portions of FIG. 6;

FIG. 8 is a section view taken along the direction of the 8--8 arrow mark shown in FIG. 7; and,

FIG. 9 is a section view of a second embodiment of a continuously variable transmission according to a second embodiment of the invention, corresponding to FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, a description will be provided below of preferred embodiments for carrying out the invention based on a toroidal-type continuously variable transmission according to the present invention shown in the accompanying drawings.

FIGS. 1-8 show a first embodiment of a toroidal-type continuously variable transmission according to the invention. As shown in FIG. 1 and FIGS. 3-5, a continuously variable transmission for a vehicle includes a toroidal-type continuously variable transmission T, a planetary gear mechanism P of a single pinion type, a forward start clutch C1 (which is hereinafter referred to as a first clutch C1) composed of a wet type clutch, and a backward start and torque split clutch C2 (which is hereinafter referred to as a second clutch C2) composed of a wet type clutch. A crankshaft 11 of an engine E is connected through a damper 12 to an input shaft 13 of the toroidal-type continuously variable transmission T. A first shaft 14, a second shaft 15 and a third shaft 16 are disposed respectively in parallel to the input shaft 13 of the toroidal-type continuously variable transmission T. The first clutch C1 is disposed on the left end portion of the third shaft 16, while the second clutch C1 is disposed on the right end portion of the second shaft 15. A drive sprocket 17, which is fixed to the input shaft 13 of the toroidal-type continuously variable transmission T, is connected by an endless chain 19 to a driven sprocket 18 supported on the right end portion of the second shaft 15, while the second shaft 15 and driven sprocket 18 are arranged so as to be rotatable with respect to each other. Therefore, the driven sprocket 18 on the second shaft 15 and a clutch outer 20 of the second clutch C2 formed integral with the driven sprocket 18 are normally allowed to rotate while the engine E is in operation.

To the first shaft 14 which is supported in a casing by a ball bearing 21 and a roller bearing 22, there are fixed a double helical gear 23 and a first helical gear 24; and, the double helical gear 23 is meshingly engaged with an output gear 25 which is provided in the toroidal-type continuously variable transmission T and is composed of a similar double helical gear, while the first helical gear 24 is meshingly engaged with a second helical gear 27 fixed to a sleeve 26 which can be fitted with the third shaft 16 in such a manner that the sleeve 26 and the third shaft 16 can be rotated with respect to each other. To a sleeve 30 which can be mutually rotatably fitted with the second shaft 15 supported on the casing by a ball bearing 28 and a roller bearing 29, there is fixed a third helical gear 31, while the third helical gear 31 can be meshingly engaged with a fourth helical gear 33 fixed to a sleeve 32 which can be fitted with the outer periphery of the sleeve 26 of the third shaft 16 in such a manner that they can be rotated with respect to each other. A fifth helical gear 34 is supported on the second shaft 15 in such a manner that they can be rotated with respect to each other, while the fifth helical gear 34 can be meshingly engaged through a seventh helical gear 36 with a sixth helical gear 35 fixed to the third shaft 16. The seventh helical gear 36 is a reverse idle gear but is not shown in FIG. 4. The sleeve 30 (and thus the third helical gear 31) and fifth helical gear 34 can be selectively connected to the second shaft 15 by a shifter S. To the second shaft 15, there is fixed a clutch inner 38 of the second clutch C2 and, therefore, in case where the second clutch C2 is fastened, the driven sprocket 18 is connected to the second shaft 15.

A planetary gear mechanism P, which is disposed on the third shaft 16, includes a sun gear 39 fixed to the sleeve 26, a ring gear 40, and a plurality of pinions 43--which are rotatably supported through a plurality of pinion shafts 42--on a carrier 41 fixed to the sleeve 32 and can be meshingly engaged with the sun gear 39 and ring gear 40. The first clutch C1 comprises a clutch outer 44 formed integral with the ring gear 40 of the planetary gear mechanism P and the third shaft 16, and a clutch inner 45 formed integral with the sun gear 39 and sleeve 26. Therefore, in case where the first clutch C1 is fastened, the planetary gear mechanism P is locked, so that the third shaft 16 connected to the ring gear 40, the sleeve 26 connected to the sun gear 39 and the sleeve 32 connected to the carrier 41 can be connected together as a united body. A final drive gear 46, which is fixedly disposed on the right end of the third shaft 16, is meshingly engaged with a final driven gear 48 which is disposed on a differential gear 47. The third shaft 16 is supported on the casing by a ball bearing 49 disposed on the outer periphery of the sleeve 32 and a ball bearing 50 disposed on the outer periphery of the present third shaft 16.

Next, a description will be provided below of the structure of the toroidal-type continuously variable transmission T.

On the input shaft 13 of the toroidal-type continuously variable transmission T connected to the crankshaft 11 of the engine E through the damper 12, there are supported a first continuously variable transmission mechanism 61a and a second continuously variable transmission mechanism 61b which are substantially the same in structure. The first continuously variable transmission mechanism 61a includes a substantially-cone-shaped input disk 62 fixed to the input shaft 13, a substantially-cone-shaped output disk 63 rotatably supported on the input shaft 13, and a pair of power rollers 66, 66 which are rotatably supported on their associated roller shafts 64, inclinably supported on their associated trunnion shafts 65, 65, and can be contacted with the input disk 62 and output disk 63. Between the mutually opposing surfaces (which are respectively formed of toroidal curved surfaces) of the input and output disks 62 and 63, there are formed cavities in which the power rollers 66, 66 can be stored. In case where the power rollers 66, 66 are incliningly rotated around their associated trunnion shafts 65, 65, the contact points of the power rollers 66, 66 with respect to the input and output disks 62 and 63 are caused to vary.

The second continuously variable transmission mechanism 61b is disposed substantially surface symmetric with respect to the first continuously variable transmission mechanism 61a with the output gear 25 between them.

Thus, in the case where the power rollers 66, 66 are incliningly rotated in the direction of an arrow mark a, the contact points of the power rollers 66, 66 with the input disk 62 are moved with respect to the input shaft 13 outwardly in the radial direction thereof as well as the contact points of the power rollers 66, 66 with the output disk 63 are moved with respect to the input shaft 13 inwardly in the radial direction thereof and, therefore, the rotation speed of the input disk 62 is increased and the thus increased rotational movement of the input disk 62 is transmitted to the output disk 63, with the result that the ratio of the toroidal-type continuously variable transmission T is caused to vary toward the OD side continuously. On the other hand, in case where the power rollers 66, 66 are incliningly rotated in the direction of an arrow mark b, the contact points of the power rollers 66, 66 with the input disk 62 are moved with respect to the input shaft 13 inwardly in the radial direction thereof as well as the contact points of the power rollers 66, 66 with the output disk 63 are moved with respect to the input shaft 13 outwardly in the radial direction thereof; and, therefore, the rotation speed of the input disk 62 is decreased and the thus decreased rotational movement of the input disk 62 is transmitted to the output disk 63, with the result that the ratio of the toroidal-type continuously variable transmission T is caused to vary toward the LOW side continuously.

Next, description will be given below further of the structure of the toroidal-type continuously variable transmission T with reference to FIG. 3 as well as FIGS. 6 to 8.

The input disk 62 of the first continuously variable transmission mechanism 61a is formed integrally with the input shaft 13 which is supported in the casing by a pair of roller bearings 67, 68. Because the input shaft 13 is supported by the roller bearings 67, 68, it is not restricted in the axial direction with respect to the casing. The output disks 63, 63 of the first and second continuously variable transmission mechanisms 61a, 61b are integrally connected to each other through a pin 37; and also, these output disks 63, 63 are respectively supported on the input shaft 13 through their associated needle bearings 69, 69 in such a manner that they can be rotated with respect to each other as well as can be slided in the axial direction. The output gears 25, which are respectively disposed on the outer peripheries of the pair of output disks 63, 63, are composed of a double helical gear the tooth groove of which has an angular shape, while the output gears 25 can be meshingly engaged with the double helical gear 23 formed on the first shaft 14. Because the first shaft 14 the left end of which is supported on the casing by the ball bearing 21 is restricted in such a manner that it cannot be moved in the axial direction, the output gear 25 to be meshingly engaged with the double helical gear 23 formed integral with the first shaft 14 can be positioned in the axial direction of the input shaft 13.

The input disk 62 of the second continuously variable transmission mechanism 61b is supported on the input shaft 13 through a roller spline 70 in such a manner that it cannot be rotated with respect to the input shaft 13 but can be slided in the axial direction of the input shaft 13. On the left end of the input shaft 13, there is disposed a cylinder 71 in such a manner that it is coaxial with the input shaft 13; and, between the interior portion of the cylinder 71 and the input disk 62 of the second continuously variable transmission mechanism 61b which can be slidably fitted with the cylinder 71, there is formed an oil chamber 72. Therefore, in case where oil pressure is supplied to the oil chamber 72, the input disk 62 of the second continuously variable transmission mechanism 61b as well as the output disks 63, 63 of the first and second continuously variable transmission mechanisms 61a, 61b are pressed toward the input disk 62 of the first continuously variable transmission mechanism 61a, thereby being able to generate a load which can prevent slippage between the input disks 62, 62, output disks 63, 63 and the power rollers 66,--.

A pair of right and left trunnions 73, 73 supporting the pair of power rollers 66, 66 are disposed in such a manner that they hold the input shaft 13 between them. Each of the two trunnions 73, which is formed similar in shape to a crankshaft of a single-cylinder engine, comprises a pair of journal portions 73a, 73b, which are disposed on the trunnion shaft 65 and are spaced from each other, and a U-shaped eccentric portion 73c for connecting together the mutually opposing end portions of the two journal portions 73a, 73b as a united body. A pair of actuators 75, 75, which are disposed on an oil pressure control block 74, are respectively composed of: piston rods 76, 76 respectively connected to the lower journal portions 73b, 73b of the trunnions 73, 73; cylinders 77, 77 disposed in the oil pressure control block 74; pistons 78, 78 respectively fitted with the cylinders 77, 77 and fixed to the piston rods 76, 76; upper oil chambers 79, 79 formed upwardly of the pistons 78, 78; and, lower oil chambers 80, 80 formed downwardly of the pistons 78, 78.

The journal portions 73a, 73b of each trunnion 73 and piston rod 76 are disposed so as to be coaxial with the trunnion shaft 65 and, therefore, the trunnion 73 and piston rod 76 can be incliningly rotated around the trunnion shaft 65 with the journal portions 73, 73b as the support shafts thereof. Also, in case where oil pressure is supplied to the lower oil chamber 80 of one oil pressure actuator 75, then oil pressure is supplied to the upper oil chamber 79 of the other oil pressure actuator 75. Therefore, the right and left piston rods 76, 76 are driven in the mutually opposite directions; and, in the case of the right and left trunnions 73, 73, when one of them is moved upward along the trunnion shaft 65, the other is moved downward along the trunnion shaft 65. As a result of this, the power rollers 66, 66 are rotated together with the trunnions 73, 73 around their respective trunnion shafts 65, 65 and thus the contact points of the power rollers 66, 66 with the input disk 62 and output disk 63 are moved, so that the ratio of the toroidal-type continuously variable transmission T is caused to vary continuously.

In order to make sure that the upward and downward movements of a total of four trunnions 73--of the toroidal-type continuously variable transmission T can be synchronized with each other, the upper end portions of the trunnions 73 are connected together by an upper yoke 81 and the lower end portions of the trunnions 73 are connected together by a lower yoke 82. That is, the right and left two end portions of the upper yoke 81 are pivotally supported swingably and rotatably on the upper end portions of the trunnions 73--through spherical joints 84--, while the right and left two end portions of the lower yoke 82 are pivotally supported swingably and rotatably on the lower end portions of the trunnions 73--through spherical joints 86--.

Pivot shafts 87, 87 for supporting the power rollers 66, 66 on the trunnions 73, 73 respectively include: trunnion support portions 89, 89 rotatably supported in blind-hole-shaped axial holes 73d, 73d, which are formed in the eccentric portions 73c, 73c of the trunnions 73, 73, through needle bearings 88, 88; and, power roller support portions 91, 91 for supporting the power rollers 66, 66 rotatably through needle bearings 90, 90. One of the pivot shafts 87 is structured such that the trunnion support portion 89 thereof is set eccentric downwardly with respect to the power roller support portion 91 thereof, while the other pivot shafts 87 is structured such that the trunnion support portion 89 thereof is set eccentric upwardly with respect to the power roller support portion 91 thereof.

To the trunnion support portions 91, 91 of the pivot shafts 87, 87, there are fixed disk-shaped thrust support members 93, 93. Between the thrust support members 93, 93 and power rollers 66, 66, there are interposed ball bearings 92, 92; and, between the thrust support members 93, 93 and the eccentric portions 73c, 73c of the trunnions 73, 73, there are interposed thrust bearings 95, 95. Thanks to this structure, while the loads applied to the power rollers 66, 66 from the input disk 62 and output disk 63 are being transmitted to the eccentric portions 73c, 73c of the trunnions 73, 73, not only the smooth rotation of the power roller 66, 66 with respect to the pivot shafts 87, 87 but also the smooth rotation of the thrust support members 93, 93 with respect to the eccentric portions 73c, 73c of the trunnions 73, 73 can be realized.

The mutually opposing end portions of the upper and lower journal portions 73a, 73b of each trunnion 73 are connected together by a reinforcing member 96. That is, the reinforcing member 96 includes upper and lower stepped portions 96a, 96b; and, after the stepped portions 96a, 96b are mounted between the mutually opposing end portions of the upper and lower journal portions 73a, 73b of the trunnion 73, the stepped portions 96a, 96b are fastened to the journal portions 73a, 73b by bolts 97, 97 which are respectively penetrated through the two end fixed portions 96c, 96d. In a state where the reinforcing member 96 is mounted to the trunnion 73, the two side surfaces of the power rollers 66, 66 in the pivot shaft 87 direction thereof are held by and between the eccentric portion 73c of the trunnion 73 and reinforcing member 96. Since the reinforcing member 96 is disposed opposed to the axial end of the power roller support portion 91, with no provision of a special removal preventive member such as a clip, not only removal of the pivot shaft 87 from the axial hole 73d of the eccentric portion 73c of the trunnion 73 but also removal of the power roller 66 from the pivot shaft 87 can be prevented.

In each piston rod 76 and each trunnion 73, there are formed oil passages P1-P8, while the oil passages P5 and P6 communicate with each other through the interior portion of the needle bearing 88 supporting the pivot shaft 87. One end of the oil passage P3 is opened in the bearing portion of the inner periphery of a spherical joint 86 which supports the lower yoke 82, one end of the oil passage P5 is opened in the slide surface of the outer periphery of the spherical joint 86, one end of the oil passage P6 is opened in the slide surface of the outer periphery of a spherical joint 84 supporting the upper yoke 81, and one end of the oil passage P7 is opened in the slide surface of the inner periphery of the spherical joint 84. And, the thrust bearing 95, ball bearing 92 and needle bearing 90 are lubricated through oil passages P9-P14 which respectively branch off from the oil passages P5 and P6.

Also, the oil passages P4 and P8, which are formed in the journal portions 76a, 76b of the trunnion 76, are in communication with a pair of oil passages P15, P16 formed in the reinforcing member 96, while the pair of oil passages P15, P16 are opened toward the surface of the power roller 66. Therefore, the power roller 66 can be lubricated sufficiently with lubricating oil which is supplied from the oil passages P15, P16 and also, since the oil passages P15, P16 are opened at a position adjacent to the surface of the power roller 66, the lubricating oil can be prevented from spraying around, thereby being able to enhance the lubricating effect.

For lubrication of the input and output disks 62, 63, a closed portion formed in the leading end portion of a flexible lubricating oil pipe 98 is fixed to the upper yoke 81, whereas an opening formed in the base end portion of the lubricating oil pipe 98 is penetrated through the lower yoke 82 and is connected into an oil passage 99 formed in the oil pressure control block 74. In the middle portion of the lubricating oil pipe 98, there is formed a curved portion 98a which can prevent its interference with respect to the input shaft 13 and, on the upper and lower sides of the curved portion 98a as well as on the right and left sides thereof, there are formed a total of four lubricating oil jet-outports 98b--which are used to jet out the lubricating oil toward the input and output disks 62, 63. Therefore, the lubricating oil supplied from the base end side of the lubricating oil pipe 98 can be jetted out from the lubricating oil jet-out ports 98b--, so that the surfaces of the input and output disks 62, 63 can be lubricated effectively.

Next, description will be given below of the transmission operation of the toroidal-type continuously variable transmission T having the above-mentioned structure.

Firstly, description will be given below of the transmission operation in the case of the forward running operation of a vehicle.

In the forward running operation, the shifter S is switched over to the forward running side (in FIG. 1, in the direction of an arrow mark F). Firstly, with the toroidal-type continuously variable transmission T switched over to a LOW ratio, the vehicle is started and is then accelerated until the toroidal-type continuously variable transmission T reaches an OD ratio. This running mode is referred to as a direct mode. In the direct mode, with the second clutch C2 remaining held in a non-fastened state, only the first clutch C1 is fastened. That is, in FIGS. 1 and 4, in case where the first clutch C1 is fastened, the ring gear 40 and sun gear 39 are united together and the planetary gear mechanism P is thereby locked, so that the torque of the engine E can be transmitted through the toroidal-type continuously variable transmission T and first clutch C1 to drive wheels W, W. Specifically, the torque of the engine E is transmitted in the route of crankshaft 11-damper 12-input shaft 13 of toroidal-type continuously variable transmission T-output gear 25 of toroidal-type continuously variable transmission T-double helical gear 23-first helical gear 24-second helical gear 27-sleeve 26-first clutch C1 third shaft 16-final drive gear 46-final driven gear 48-differential gear 47-drive wheels W, W, thereby causing the vehicle to run forward.

During the above operation, the rotation of the carrier 41 of the planetary gear mechanism P is transmitted in the route of sleeve 32-fourth helical gear 33-third helical gear 31-sleeve 30-shifter S-second shaft 15-clutch inner 38 of second clutch C2; and, because the second clutch C2 is held in a non-fastened state, there is no possibility that this rotation can be interfered with by the clutch outer 20 of the second clutch C2 connected to the input shaft 13 through the drive sprocket 17, endless chain 19 and driven sprocket 18.

Thus, after the first clutch C1 is fastened completely, while shifting the ratio of the toroidal-type continuously variable transmission T from LOW to OD, the vehicle is accelerated. The ratio width during this is 5.8 which is a ratio of the LOW ratio (2.415) and OD ratio (0.415) of the toroidal-type continuously variable transmission T.

In the case where the toroidal-type continuously variable transmission T reaches the OD ratio, the fastened state of the first clutch C1 is removed, the second clutch C2, which has been held in the non-fastened state, is fastened, and the ratio of the toroidal-type continuously variable transmission T is shifted from OD to LOW. Due to this, the ratio of the entire continuously variable transmission can be shifted to the higher ratio side than the highest ratio, that is, OD ratio of the single toroidal-type continuously variable transmission T and thus the ratio width of the direct mode, 5.8 can be extended up to 8.7. This running mode is referred to as a torque split mode.

In the torque split mode, the torque of the engine E is transmitted to the carrier 41 of the planetary gear mechanism P through the route of crankshaft 11-damper 12-input shaft 13 of toroidal-type continuously variable transmission T-drive sprocket 17-endless chain 19-driven sprocket 18-clutch outer 20 of second clutch C2-clutch inner 38 of second clutch C2-second shaft 15-shifter S-sleeve 30-third helical gear 31-fourth helical gear 33-sleeve 32. Most of the torque of the carrier 41 of the planetary gear mechanism P is transmitted in the route of ring gear 40-clutch outer 44 of first clutch C1-third shaft 16-final drive gear 46-final driven gear 48-differential gear 47-drive wheels W, W, thereby being able to drive the vehicle forward. Also, part of the torque of the carrier 41 of the planetary gear mechanism P is transmitted reversely to the input shaft 13 of the toroidal-type continuously variable transmission T in the route of sun gear 39 of planetary gear mechanism P-sleeve 26-second helical gear 27-first helical gear 24-double helical gear 23-output gear 25; and, the torque is transmitted from the input shaft 13 to the drive wheels W, W through the above-mentioned route passing the second clutch C2.

In the case where the toroidal-type continuously variable transmission T is shifted from the OD ratio side to the LOW ratio side in the torque split mode, the ratio of the entire continuously variable transmission is shifted to the further higher ratio side. The reason for this is that, in case where the toroidal-type continuously variable transmission T turns into the LOW ratio and then the number of rotations of the output gear 25 is thereby reduced, the number of rotations of the sun gear 39 of the planetary gear mechanism P is reduced and, in accordance with this, the number of rotations of the ring gear 40 of the planetary gear mechanism P connected to the drive wheels W, W is increased.

Next, description will be given below of the gear change operation in the backward running operation of the vehicle.

In the backward running operation of the vehicle, while holding the toroidal-type continuously variable transmission T in the LOW ratio, the vehicle is started. In this case, while the first clutch C1 remains held in the non-fastened state, only the second clutch C2 is fastened. That is, in FIGS. 1 and 4, in case where the second clutch C2 is fastened, the torque of the engine E is transmitted in the route of crankshaft 11-damper 12-input shaft 13 of toroidal-type continuously variable transmission T-drive sprocket 17-endless chain 19-driven sprocket 18-second clutch C2-second shaft 15-shifter S-fifth helical gear 34-seventh helical gear 36-sixth helical gear 35-third shaft 16-final drive gear 46-final driven gear 48-differential gear 47-drive wheels W, W, thereby driving the vehicle backward. During this, the rotation of the output gear 25 of the toroidal-type continuously variable transmission T is input to the sun gear 39 of the planetary gear mechanism P, is output from the carrier 41 and is transmitted to the sleeve 30 of the second shaft 15 and, because the shifter S is switched over to the backward running side, there is no possibility that the present rotation can interfere with the rotation of the second shaft 15.

By the way, while the toroidal-type continuously variable transmission T is in operation, in the case where operation oil of high pressure is supplied into the oil chamber 72 formed within the cylinder 71, the left-side input disk 62, which can be slided with respect to the input shaft 13, is energized in the right direction. The energizing force of the left-side input disk 62 is transmitted through the left-side power rollers 66, 66, centrally situated output disks 63, 63 slidable in the axial direction with respect to the input shaft 13, and right-side power rollers 66, 66 to the right-side input disk 62 which is formed integral with the input shaft 13. As a result of this, the power rollers 66, 66 of the right-side first continuously variable transmission 61 a are strongly held by and between the right-side input disk 62 and output disk 63, while the power rollers 66, 66 of the left-side second continuously variable transmission 61b are strongly held by and between the left-side input disk 62 and output disk 63, so that the torque can be transmitted without causing any slippage.

The input shaft 13 is supported on the casing by the roller bearing 67, 68 in such a manner that it can be moved in the axial direction, and the left-side input disk 62 and central output disks 63, 63 are all slidable with respect to the input disk 13 in the axial direction of the input disk 13 and, therefore, the power rollers 66, 66 of the right-side first continuously variable transmission mechanism 61a and the power rollers 66, 66 of the left-side second continuously variable transmission mechanism 61b are pressed with equal pressure, which not only makes uniform the transmission characteristics of the first and second continuously variable transmission mechanisms 61a and 61b but also prevents the load of the cylinder 71 from being transmitted as a thrust force from the input shaft 13 to the casing.

Also, the output gear 25, which consists of a double helical gear formed integral with the central output disks 63, 63, is in meshing engagement with the double helical gear 23 of the first shaft 14, while the first shaft 14 is positioned by the ball bearing 21 with respect to the casing in the axial direction thereof. Therefore, the input shaft 13 is positioned with respect to the casing in the axial direction thereof indirectly through the output disks 63, 63, output gear 25, double helical gear 23, first shaft 14 and ball bearing 21, which can prevent the input shaft 14 from moving unexpectedly.

Further, because the input shaft 13 is not restricted in the axial direction thereof, even in the case where the load from the cylinder 71 is applied, the meshingly engaged portions of the output gear 25 and double helical gear 23 are prevented from shifting, which can prevent uneven thrust forces from occurring in the meshingly engaged portions. This can prevent occurrence of a difference between the loads of the power rollers 66, 66 of the first and second continuously variable transmission mechanisms 61a and 61b, thereby being able to keep uniform the transmission characteristics of these two continuously variable transmission mechanisms 61a and 61b.

As described above, in the case where the power rollers 66--of the first and second continuously variable transmission mechanisms 61a and 61b are pressed by and between the input disks 62, 62 and output disks 63, 63, a load, which is shown by an arrow mark F in FIG. 7, is applied to the power roller 66 to try to deform the trunnion 73. However, because the reinforcing member 76 is fixed in such a manner that it bridges the eccentric portion 73c (which is lowest in rigidity) of the trunnion 73, the deformation of the trunnion 73 can be controlled down to a minimum and thus the piston 78 disposed on the lower journal portion 73b of the trunnion 73 through the piston rod 76 can be prevented against the frictional action, which can guarantee the smooth operation of the trunnion 73. Also, the support surfaces of the ball bearing 92 and thrust bearing 95 supporting the power roller 66 on the eccentric portion 73c of the trunnion 73 can be prevented against deformation, thereby being able to extend the lives of the ball bearing 92 and thrust bearing 95.

Next, description will be given below of a second embodiment of a double cavity toroidal-type continuously variable transmission according to the invention with reference to FIG. 9.

In the second embodiment, the input shaft 13 of the toroidal-type continuously variable transmission T is divided into a first shaft part 13a and a second shaft part 13b. The first shaft part 13a, which is connected to a crankshaft 11 and supports a damper 12 and a pump driving sprocket 100, is supported on the casing by a ball bearing 68'. The right-end outer periphery of the second shaft part 13b supporting first and second continuously variable transmission mechanisms 61a, 61b is coaxially fitted with the left-end inner periphery of the first shaft portion 13a, while the second shaft part 13b is allowed to move in the axial direction thereof with respect to the first shaft part 13a. A drive sprocket 17 formed integral with the first shaft part 13a is connected to a flange 101 which is formed integral with the second shaft part 13b through an Oldham coupling 102. The left end portion of a first shaft 14 is supported on the casing by a roller bearing 21' which receives a radial load, whereas the right end portion of the first shaft 14 is supported on the casing by a ball bearing 22' which receives a thrust load.

The left end portion of the second shaft part 13b of the input shaft 13 of the toroidal-type continuously variable transmission T is supported on the casing by a roller bearing 67, whereas the right end portion thereof is fitted with the left end portion of the first shaft part 13a and, therefore, the second shaft part 13b is allowed to move in the axial direction with respect to the casing. However, the second shaft part 13b of the input shaft 13 is connected through an output gear 25 and a double helical gear 23 to the first shaft 14, the axial movement of which is restricted by the ball bearing 22', so that the axial movement of the second shaft part 13b can be restricted. Thanks to this, in the second embodiment of the present invention as well, there can be provided operation effects which are similar to the previously described first embodiment. Also, even in the case where the second shaft part 13b of the input shaft 13 moves in the axial direction, because the first shaft 13a is prevented from moving in the axial direction with respect to the casing, it is possible to prevent a load from being applied to a spline which supports the damper 12 and pump driving sprocket 100 on the first shaft part 13a.

Although description has been given heretofore in detail of the embodiments of the invention, the invention can also be changed in design in various manners without departing from the subject matter of the invention.

For example, in the illustrated embodiments, the output disks 63, 63 of the first and second continuously variable transmission mechanisms 61a, 61b are composed of two members and are united together as an integral body. However, they can also be composed of a single member. Also, in the illustrated embodiments, as the energizing unit, there is employed the cylinder 71 but, instead of the cylinder 71, there can also be employed a torque cam mechanism which is conventionally known. Further, in the case of the double helical gear, a pair of helical gears may be composed of two members or a single member, provided that the pair of helical gears have opposite tooth groove directions and thus they are prevented against relative rotation with respect to each other.

As has been described hereinbefore, according to the first aspect of the invention, even in the case where the axial-direction position of the output disk with respect to one input disk fixed to the input shaft is varied by the energizing force of the energizing unit energizing the other input disk, which is supported on the input shaft so as to be movable in the axial direction thereof, toward one input disk, because the axial-shift allowed input shaft and the axial-shift restricted output shaft are connected together by drive and driven gears respectively composed of double helical gears which are prevented from rotating with respect to each other, the axial-direction shift of the input shaft can be restricted by the output shaft. As a result of this, while positioning the input shaft in the axial direction, not only the load of the input shaft can be prevented from being transmitted therefrom to the casing but also the loads, which are applied from the energizing unit to the power rollers stored in the pair of cavities, can be prevented from differing from each other.

Claims

1. A double cavity toroidal continuously variable transmission, comprising:

an input shaft;

a pair of input disks disposed on outer portions of said input shaft in an axial direction of said input shaft, one input disk being fixed to said input shaft, the other input disk being supported thereon so as to be movable in the axial direction thereof;

a pair of output disks respectively supported on an inner portion of said input shaft in the axial direction thereof so as to be movable in the axial direction thereof, said output disks respectively including drive gears;

an energizing unit energizing said other input disk toward said one input disk;

power rollers respectively stored in a pair of cavities formed between each said mutually opposing input disk and output disk, said power rollers being contacted with said input disk and said output disk; and,

an output shaft having driven gears being meshingly engaged with said drive gears of said output disks,

wherein said input shaft is allowed to shift in the axial direction thereof said output shaft is prevented from shifting in the axial direction thereof, and said drive gears are respectively structured by double helical gears and said driven gears are respectively structured by double helical gears,

wherein said drive gears are prevented from relatively rotating with respect to each other and said driven gears are prevented from relatively rotating with respect to each other.

2. The double cavity toroidal continuously variable transmission according to claim 1, wherein said one input disk is formed integrally with said input shaft as a unitary member.

3. The double cavity toroidal continuously variable transmission according to claim 2, wherein said input shaft is supported on a casing through roller bearings, and said output shaft is supported on said casing through a ball bearing.

4. The double cavity toroidal continuously variable transmission according to claim 1, wherein said input shaft comprises:

a first shaft portion rotatably supporting said input disks and said output disks, said first shaft portion being allowed to shift in the axial direction thereof; and

a second shaft portion disposed coaxial with said first shaft portion in such a manner as to slidably fit one end portion of said first shaft portion therewith, said second shaft portion being prevented from shifting in the axial direction thereof.

5. The double cavity toroidal continuously variable transmission according to claim 4, wherein said second shaft portion is supported on a casing through a ball bearing, said first shaft portion is supported on said casing through a roller bearing disposed on the other end portion thereof and the slidable-fitting with said second shaft portion, and said output shaft is supported on said casing through a ball bearing.

6. The double cavity toroidal continuously variable transmission according to claim 1, wherein each of said power rollers is rotated around a trunnion shaft to thereby shift the contact positions of said power roller with said input disk and said output disk for transmission.

7. The double cavity toroidal continuously variable transmission according to claim 1, wherein said input shaft is supported on the casing so as to be movable in the axial direction.

8. The double cavity toroidal continuously variable transmission according to claim 1, wherein said drive gears are respectively disposed on the outer peripheries of the pair of output disks.